The truth is that killing innocent people is always wrong - and no argument or excuse, no matter how deeply believed, can ever make it right. No religion on earth condones the killing of innocent people; no faith tradition tolerates the random killing of our brothers and sisters on this earth.
I don't believe that if you do good, good things will happen. Everything is completely accidental and random. Sometimes bad things happen to very good people and sometimes good things happen to bad people. But at least if you try to do good things, then you're spending your time doing something worthwhile.